The blue-green crystals in this sample are dioptase, most likely sourced from the Tsumeb mine in Namibia. Dioptase is a mineral that contains copper, silicon, oxygen, and hydrogen, so it would be classified as a hydrated copper silicate. Chemically, it typically forms when fluids interact with copper bearing sulfide minerals – the reaction of sulfur with water gives off acid that allows metals like copper to dissolve. If the acidic fluid then finds something to neutralize the acid, such as the carbonate minerals found in this sample, the metal will precipitate to form new crystals at that spot.

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Smithsonite (fluorescent) on Willemite (fluorescent)

Smithsonite (fluorescent) on Willemite (fluorescent)
Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia
Miniature, 5.3 x 3.2 x 2.5 cm
This is one of the sparkliest, most interesting Tsumeb combination piece I have had. Smithsonite and Willemite are certainly two of Tsumeb’s prize species, and together they make a rare, and exemplary combination piece.

Visit the site to see photos of this piece under fluorescent lighting!

Duftite in calcite

The lovely green inclusions scattered in zones in the white calcite crystal are a complex hydrated lead copper arsenate )plus a dash of calcium and zinc, sometimes) mineral that formed when an anoxic primary ore deposit was altered by oxygen rich waters in the land now known as Namibia. Any mineral collector’s body hairs will stand up when the word Tsumeb is uttered, that fount of many mineral wonders in the middle of the Namibian desert (see http://on.fb.me/1c2CjkD for an account) . Duftite was named after the manager of this famed mine and is often found accompanying other rare and beautiful oxidation products. The usual colour is green, in varied shades and the lead content makes the mineral very dense in the hand. As well as Namibia, it is also found in Morocco, France, Germany, Russia, England, Mexico, the United States, and Australia.


Image credit: fosagams.co.za